1. Field of the Invention
The present invention relates to footwear. The invention concerns, more particularly, an article of footwear having a sole portion that is removable or otherwise separable from a foot-receiving portion.
2. Description of Background Art
The various styles of conventional footwear include athletic footwear, sandals, dress shoes, and boots, for example, and are generally formed of two primary elements, an upper and a sole structure. The specific configuration of the upper and sole structure varies significantly depending upon the style of footwear and the intended use for the footwear. With regard to athletic footwear, for example, the upper may cover the entire foot and is generally formed of lightweight components. The sole structure is formed of multiple layers, including a midsole and an outsole. The midsole attenuates ground reaction forces and absorbs energy upon impact with the ground. The outsole provides a durable, wear-resistant surface and may include texturing to enhance traction. In addition, the sole structure of athletic footwear may include an insole that is positioned within the upper and adjacent to the sole of the foot in order to enhance the comfort of the footwear. The insole is often secured within the upper with an adhesive to prevent the insole from moving relative to the footwear.
Although conventional articles of footwear vary greatly with respect to the configuration of the upper and the sole structure, a common feature of most conventional articles of footwear is that the upper and sole structure are permanently attached to each other.
Although this configuration is well-established in the footwear industry and accepted by consumers, this configuration leads to footwear that may not have optimum durability. When one of the upper or sole structure becomes worn or damaged, the entire article of footwear becomes unusable.
Footwear having a permanently attached upper and sole structure may also have issues with respect to cleansing. The upper and insole, for example, may be formed of cloth or other porous materials and the sole structure may incorporate a lightweight foam material such as polyurethane or ethylvinylacetate. Cleansing conventional articles of footwear may prove difficult due to inaccessibility of the insole and the differing cleansing requirements of the cloth and foam components.
Customizing footwear may be important to consumers from a structural and aesthetic perspective. With respect to conventional footwear, the consumer has few options regarding the manner in which the footwear is fitted because manufacturers generally provide a specific combination of upper and sole structure having specific sizes. The consumer also has few options regarding the material forming the insole or the footbed contour. In addition, the consumer must accept the color combinations and styling provided by the manufacturer.
In an attempt to provide consumers with footwear that overcome one or more of these issues, a plurality of footwear designs wherein the upper is separable from the sole structure have been advanced. U.S. Pat. No. 5,083,385 to Halford discloses an article of footwear with an interchangeable upper. The sole structure has an outsole with vertical walls that extend upward from the outsole. The upper, which is permanently attached to an insole, is placed within the indentation formed by the outsole and walls to secure the upper to the sole structure. U.S. Pat. Nos. 5,852,885 and 5,802,738 to Ferniani disclose a sandal having a separable upper and sole structure, and the upper includes tabs that may be coupled with the sole to attach the upper to the sole structure.